Introduction to Haidai Metropolis: Haidai Metropolis is a testament to Qingzhou’s history as the political, economic and cultural center of Shandong. Qingzhou is located between Hai (East China Sea) and Dai (Mount Tai). It has been a metropolis and a military center in the past. It has long been the political, economic, cultural, and military center of Shandong. With developed commerce and merchants, Qingzhou is known as the "Three Qi Important Towns". , Haidai Metropolis". In order to highlight the historical status of ancient Qingzhou, this archway was established and is one of the landmark buildings in the ancient city of Qingzhou. The square has four pillars and three doors, with a total height of 9.4 meters and a total width of 14.4 meters. The middle door is wide and can pass through for carriages and horses. Under normal circumstances, officials can go through the middle, and civilians can go through the small doors on both sides.